In this post, I’m documenting the progress of my road-salt-in-my-drinking-water experiment.
Recall that:
- We had a half-inch of rain Friday 1/31/2025 that washed away the piles of road salt that remained from an earlier winter storm.
- It should take about a week for water to work its way from the Potomac River to my tap, per Fairfax County.
- Nothing filters salt out of the water, so the salt that got washed off the roads should show up in my tap any day now.
- After correcting for operator error, my tap water has shown a steady 210 ppm (parts-per-million) TDS (total dissolved solids) for the entire past week.
I am pleased (?) to report that last night’s water sample clocked in at 232 ppm. And as of 2/8/2025, it had risen to 242 ppm.
Assuming that was not a fluke, I expect that was the beginning of the salt passing through my fresh water system. The timing is right, in any case.
I’ll be tracking this for another few days, and will continue to document the results, here in this post.
Update 2/16/2025 PM sample: Tap water TDS returns to baseline level.
Between the time of the rain, and now, my tapwater’s TDS increased by about 100 parts per million, against a relatively stable baseline of about 200 ppm baseline. The peak occurred about 10 days after the salt-clearing rainstorm.
But even if that entire increase is, in fact, due to chloride ion from road salt, we still won’t taste it in the drinking water. The 100 ppm (presumed) chloride ion concentration in the drinking water is well below the threshold (250 ppm) above which (some? many?) people will detect a “salty” taste to the water. The bottom line is that, so far, this should not be a generally taste-able water saltiness event.
And that’s a good thing.
In addition, it is far from proven that the uptick in TDS of my tap water is even due to road salt. E.g., maybe this happens after every significant rain. But I’m betting that’s the road salt. And even if it is driven by road salt, there has to be more in the TDS increase that just chloride ions.
It doesn’t matter. Won’t taste this amount of salt in the water, no matter how you slice it.
In summary, there was a modest increase in my tap water’s TDS. Timing is about right for this to reflect “salt in the tap water”, from road salt runoff of 1/31/2025. But nothing has been proven, except that, even worst case, the ion concentration is not nearly enough to give the water a salty taste.
Edit: As of 2/13/2025, we’re midway or better (?) through the “runoff” step of a new road salt runoff cycle. Or, if not midway, we’ll get there and beyond today, with a predicted high in the low 50s.) And so, we should see a smaller, smearier version of this most recent drinking water salt pulse … 2/21/2025. It’s not clear that this simple rig, or any simple rig, would reliably let you “see” a pulse that small and ill-defined. (And that’s assuming the measured TDS number for tap water is otherwise pretty steady from day to day.)
OTOH, it’s no hardship to keep this going. Just KISS. All it takes is this cheap TDS meter, a drinking glass, and patience.
Use just one glass. Test the water twice a day. But you need to let that cold tap water stand a good long while, if you want a reliable reading out of a slow-read $6 meter. So, let each sample sit half a day. Covered. AM and PM, you use (and rinse) the meter, dump that water sample, run the tap and replace the water sample, and set it aside, covered. Then leave it alone. Until it’s time to do all that again. Repeat twice a day.
It’s idiot-proof. And sometimes that’s a good thing.
